package com.atguigu.practice;

 class TreeNode {
      int val;
     TreeNode left;
      TreeNode right;
      TreeNode() {}
      TreeNode(int val) { this.val = val; }
      TreeNode(int val, TreeNode left, TreeNode right) {
          this.val = val;
        this.left = left;
          this.right = right;
      }
  }

public class ReverseBinaryTree {
    public TreeNode invertTree(TreeNode root) {
        if(root==null) return null;
        _invertTree(root);
        return root;
    }
    public void _invertTree(TreeNode root){
        if(root==null) return;
        TreeNode tmp=root.left;
        root.left=root.right;
        root.right=tmp;
        invertTree(root.left);
        invertTree(root.right);
    }
}
